Current responsive apparatus



Dec. 19, 1939. G, LlNGG 2,183,685

CURRENT RESPONSIVE APPARATUS FiledJan. 8, 1958 ITM/enterq '.k

Gustav Lgf-ggg His Attorney.;

' Patented D ec. 19, 1939 y UNITED; STATES .amm ouaaim'r aasrossrvr PA'iisNi'A .OFFICE l Gustav Lin", Germany, assigner to General Electriccomparan a corporation or New York Application January .8, ma; serial vNc'nmrua.

' In Germanylanuary 11, i987 l:a claims, (cmu-95V' '10 the range of the instrument.

In carrying out my invention in its preferred form I provide 'a current conducting coil with a substantially cylindrical opening therein, a stationary iron extending circumferentially along I l5 4the inner surface of the coil and tapering to a minimum width at'the upscale end, and a movable vane having an axis of rotation substantially coaxial with the coil and traveling along the' surface of the stationary iron. For expanding `the .upper end of the scale I provide one or more auxiliary irons or Vattraction irons adjustably` mounted inthe vicinity of the upscale end o f'the f path of the movable vane and extending from outside the coil into the internal space of the coil..l

The invention will be understood more readily from the following detailed description when considered in connection with the accom ing drawing and those features of the inven on so which are believed to be\novel and patentable. will be pointed out in the claims appended here-v to. In the drawing Figure l is a diagrammatic 'perspective view partially in section illustrating one embodiment of my invention. Figure 2 is a.. perspective view of a modified form of movable .vane i'or use with the apparatus of Figure 1particularly, when the main stationaryiron of Figure lis omitted, andFigureSis a diagram illustratingf the eilect of myinvention on thescale distribution or a moving vane type of instrument. In electrical instruments of the moving vane'A or induction type, the torque'depends upon' the rate of change with respect to angular deilection of the magnetic ux owing through the magnetizable members. In orderto obtain a substantially uniform scale distribution, particular ly in order to open-up the scale at the upper end where it is ordinarily crowded in induction instruments o1 the usual type, I use a'ileld congo'kstruction in which the ratetof change ot mag- `.'netzation is made more nearly uniform. The

manner in which this is'accomplished proceeds from the following consideration: The magnetic eiect or the energy in a magnetic systemis'equal to the product of the total iield strengthot the liield strength and thedii'erential of the inducrivative vof magnetic energy with respect to'an- Moreover as the magnetic energy in the iron con and the induction in the magneuzabie inembers at each instant. This magnetic energy may be ascertained by integrating the product of the tion throughout the volume in question. It the magnetic energy is denoted by Wm, the ileld strength by H and the induction by B. then-for a space of volume Vin which magnetic -ilux is induced: v

The magnetic energy may be considered separately in three portions of the space containing uxsrst that in the iron of the system, second .l5 that inside the coil# and third that outside of the coiL/Then if they subscripts 1,- 2 and3'are used to' distinguish quantities in these three portions of the space containing ux.

The moment M exerted on the rotating with a change of the angle of deflection is the deguiar de ection, equation The magnetic energy outside the4 coil ls noef-- f ect and can therefore be completely neglected.

'which may be' expressed by the considerably smaller than .in thev inside ot tlx coiLVpracticallyorlly the value magnetic Aenergy' wlthat the ends-of the scale is to be avaided, -it 'l is necessary 'that the rateof change of energy with changent the angle of deilection, 45 be not essentially altered as the movable`element deects. -Thus in approachingfull deiiection, it is necessary that -such rate of change of magnetic energy withoangle oi'4 deection be only finconsiderably aller, or even greater I0 than at thev beginning of the deilection. The formation of'. the magnitude H adBz-depends esi sentially on the magnitude of the I induction, which is particularly strong in the vicinity of the iron. Thus'if one or more additional irons. Il

which can fully or nearly fully replace the fixed iron in their action, are placed approximately at the point where the rotating iron reaches its full deflection, then the moment exerted on the rotating iron upon approaching full deflection will be considerably greater than could hitherto be obtained with the ordinary rotating iron apparatus. In particular the arrangement is made so that the magnitude of the moment exerted remains constant as far as possible in order to produce as nearly uniform as possible a scale.

In Figure 1, the principle of the invention is illustrated by a diagram in which the relative positions of the parts are shown, but unimportant units or those not directly involved in the novel principle of the invention are omitted. The actual current conducting winding or coil is likewise omitted since its position is clear from the representation of the spool-shaped winding form consisting of a cylinder I and flanges 2 and 3. The magnetic axis of the coil is the .mechanical axis of the cylinder I. A sheet of magnetizable material 4 is mounted within the cylinder I and extends circumferentially, lying conveniently against the inner surface of the cylinder I. The sheet 4 may be composed of soft iron or other suitable magnetizable material. This, for the sake of convenience, is referred to as a stationary iron although the invention is not limxo ited to the use of iron.

A movable vane 5 is provided which preferably also is formed as a portion of a surface of a cylinder and is mounted upon a shaft 5 pivotally supported with an axis substantially parallel and if desired, coincidental with the mechanical axis of the cylinder I. The vane 5 is likewise composed of any suitable magnetizable material such as soft iron,.for example, and its path lies along the surface of the stationary iron 4 which is either tapered in the upscale direction or is otherwise so shaped that the distances between the pole portions of the vane 5 and the polarized edges of the stationary iron 4 decrease as the vane 5 moves in the upscale direction. A biasing spring I4 or other suitable means is provided for restraining gie vane 5 against movement in the upscale direc- At a position near the upscale end of the stationary iron 4 one or more auxiliary or attraction irons 1 and 8 are mounted so as to be adjustable in position. The irons 1 and 8-may be composed of soft iron or any other suitable magnetizable material and are so shaped as to extend into the internal space of the coil surrounding the cylinder I. If desired, the irons 1 and 8 may be joined at their outer ends by a yoke portion 9. In the arrangement shown, the friction between th'e ends of the cylinder I and the irons 1 and 8, holds the member 1-8-9 but permits angular adjustment. 'i

In the descriptionland claims, I have used the term iron to vrefer generically to a`inember composed of any readily magnetized material.

'I'he operation of the instrument will be gpparent from the follcwingconsiderations. AIt will be understood that the current conducting coil produces a magnetic field extending parallel to the shaft 6 so that the irons 4 and 5 are magnetized and magnetic poles are produced at the edgesi and II of the movable iron or vane 5 and at the edges I2 and I3 vof the stationary iron 4. Adjacent edges of the irons V4 and 5 have like polarity causing repulsion between the relatively movable irons 4 and 5.

owing to the tapering of the edges I2 Aand I of the stationary iron 4, the distances between adjacent edges of the irons 4 and 5 increase as the iron 5 moves toward the left or the upscale direction and the repulsive forces, therefore, drive the iron 5 upscale. Since, as the vane 5 moves upscale, the distances between adjacent polarized edges become progressively greater, the available torque for overcoming the restraining-spring torque becomes less and less, and the upper portion of the scale of the instrument would tend to be quite crowded. However, the presence of the attraction irons 1 and 8 at the upscale end of the path of the movable vane 5 introduces an attractive force, since the irons 1 and 8 are magnetized by the field in such a manner as to have polarities opposite to the polarities of the adjacent poles of the movable vane 5. This attractive force becomes greater as the vane 5 approaches the full-scale position thereby expanding the upper portion of the scale so as to produce a substantially uniform scale. It will be understood that for the purpose of adjusting the exact shape of the -scale and varying the calibration, the attraction irons 1 and 8 are adjusted in any suitable manner "to vary their angular position on the cylinder I.

, The scale shown in Figure 3 illustrates the effect of the attraction irons 1 and 8.v The lower set of scale markings and numerals marked b represents the calibration of a repulsion instru- Vment of customary construction not having the attraction irons 1 and 8. If the attraction irons 1 and 8 are mounted at the zero position of the movable element 5, a different set of calibrations marked c is obtained which differs, however, relatively little from that of the calibration b. By mounting the attraction irons 1 and 8 at the fullscale position of the movable vane 5, as hereinbefore described, a set of calibrations d is obtained. It will be seen that the attraction irons 1 and 8 have relatively little effect on the lower half of the scale. Even the halfscale position is nearly unaffected. However, the upper portion of the scale is considerably expanded as will beseen rom the fact that f our units of current produce very nearly the same deflection on scale d as five units of current on`scale b. The criterion of the effectiveness of the upper scale compensation is the distance between the three and four ampere calibrations marked d as compared with the difference from the threeand fourv ampere calibrations marked c. It will be seen that the instrument has been made very much more sensi'- "tlve in the upper portion of the scale.

If the movable vane 5 is also tapered in the upscale-direction, the amount of attraction between the movable vane 5 and the attraction irons 1 and 8 increases as the fullscale position is ap proached. This effect may be utilized instead of the variation in repulsion between the vane 5 and the stationary iron 4 for producing deflection of the movable element and if desired, the stationary iron 4, may be omitted when a movable-vane shape as'shown in Figure 2 is employed.

I have herein shown and particularly described certain embodiments of my invention and certain methods of operation embraced therein for the purpose of explaining its principle and showing its application but it will be obvious to those skilled in the art that many modifications and variations are possible and I aim, therefore. to cover all such modifications and variations as fall within the scope of my invention which is dened in the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is: 1.. A current responsive device comprising a current conducting coil having an opening therein extending substantially parallel with the magnetic axis of said coil, astationary sheet of vmagnetizable material within said opening bent substantially along the surface of a cylinder having an axis parallel with the magnetic axis of the coil and tapering in a given direction referred to as the upscale direction, a movable vane of magnetizable material rotatably mounted to travel in proximity to the surface of said stationary sheet and an auxiliary member of magnetizable material extending into the opening in said coil and adjustably mounted at the upscale end of the stationary sheet. Y

\2. A current responsive instrument comprisinga current conducting coil, a movably mounted vane of magnetizable material in inductive relation to said coil and tapering in the upscale direction, an attraction iron extending into said coil mounted at the upscale end of the path of said vane and means for resiliently opposing movement of said vane in the upscale direction.

' GUSTAV 

